Intra-articular tissues, such as the anterior cruciate ligament (ACL), do not heal after rupture. In addition, the meniscus and the articular cartilage in human joints also often fail to heal after an injury. Tissues found outside of joints heal by forming a fibrin clot, which connects the ruptured tissue ends and is subsequently remodeled to form scar, which heals the tissue. Inside a synovial joint, a fibrin clot either fails to form or is quickly lysed after injury to the knee, thus preventing joint arthrosis and stiffness after minor injury. Joints contain synovial fluid which, as part of normal joint activity, naturally prevent clot formation in joints. This fibrinolytic process results in premature degradation of the fibrin clot scaffold and disruption of the healing process for tissues within the joint or within intra-articular tissues.
The current treatment method for human anterior cruciate ligament repair after rupture involves removing the ruptured fan-shaped ligament and replacing it with a point-to-point tendon graft. While this procedure can initially restore gross stability in most patients, longer follow-up demonstrates many post-operative patients have abnormal structural laxity, suggesting the reconstruction may not withstand the physiologic forces applied over time (Dye, 325 Clin. Orthop. 130-139 (1996)). The loss of anterior cruciate ligament function has been found to result in early and progressive radiographic changes consistent with joint deterioration (Hefti et al., 73A(3) J. Bone Joint Surg. 373-383 (1991)). As anterior cruciate ligament rupture is most commonly an injury of a young athletes, early osteoarthritis in this group has difficult consequences.
Thus, there is a need in the orthopedic art for a device that reproduces the function of the fibrin clot to re-connect extra-articular tissues in the early phase of healing. A therapeutic intervention that would facilitate anterior cruciate ligament regeneration or healing could offer several advantages over anterior cruciate ligament reconstruction. With anterior cruciate ligament regeneration or healing, the fan-shaped multiple fascicle structure could be preserved, the complex bony insertion sites could remain intact, and the proprioceptive function of the ligament could be retained.